Vibrator-exciting action



Dec. 26, 1950 B. F. MxEssNl-:R

VIBRAToR-EXCITING ACTION 2 Sheets-Sheet 1 Filed Sept. 16, 1947 INVENTOR Dec. 26, 1950 B. F. MIESSNER VIBRATOR-EXCITING ACTION 2 ShNeets-Sheet 2 Filed Sept. 1e, 1947 Gttorneg IESSIIEI l A J amm www Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE 'VIBRATOR-EXGI'IING ACTION BenjamnF. 'Miessnen Harding Township, Morris `County,.N. J., .assigner to Miessner Inventions,

Inc., Harding Township, Morris County, N. J., .a corporation of New .Iersey Application September 16, 1947', ScrialNof'l'gZSQ (Cl. @S4-2,40)

.110 lClaims. l

vThis invention relates to actions "iorithe'excitation of vibrators, such as the vibratOrsemplOyed in musical instruments. 'The invention contemplates especially, though not 'inall aspects limitatively, instruments of the piano type, wherein tuned strings or other vibrators are percussively excited'by 'hammers under the controloi a ekeyboard. The description will accordingly be pre-- sented largely with relation to lpianos.

In United States Patent No. l2,271,460 `issued January 27, 1942, on fan applicationof mine, pointed out therel'atively great complexity of a modern piano'actionof conventional design; vand I disclosed and claimed a greatly Asimiplied-action from which there were eliminated theusual escapement mechanism '(e. g., jack), Achecking mechanism Ke. g., back-check), and repetitionai'ding `mechanism r(e. yg., 'repetition lever) eyet by which excellent and in some respects improved performance was achieved. In certain subsequent patent applications (Serial No.556,1166, Vnled vSeptember 28, 1944, now abandoned; Serial `"No 566,979, led December 7, i944, `now matured into U. S. Patent No. 2,469,568, ydated'fltlay 10, 1949; and VSerial'No.707,879, led November 5, i946) 'I disclosed and Vclaimed'mo'diiic'ations of rand improvements on the lactionsdisclosed' in that patent.

In a more "recent patent application (Serial No. 760,795, filed July-14,1947) Ifdisclosed'a piano action having "certain features in common with the actions of the 'patent and applications abovementioned, but specicallydiiierent there'fromiin that it retained'thechecking mechanism, orbackcheck, of conventional actions-stilleliminating, however, the escapemen't and'repetition mechanisms. In the Aaction disclosed in thatapplica tion the underlying requirement oi "a satisfactory action-that the'hammer or other vibrator-'exciting Vmember be precluded, upon rebounding froml thevibratorv after its initial Vexcitation thereof, from re-'reboundingor` bouncing"b'ack into-a further Contact (or series vof :further contacts) with the vibrator-'was accomplished by 'a braking eiect exerted on the' hammer. Forthe exerting of vthatfbraking eirect therewas'femployed a back-check, `or means of `a generally "similar naturethough of co-ursein-anf arrangement whereinit performed `functions further thanfand` different from its functions in a-conventional action.

The back-checkWasefiectiveiy employedto exert v 'It is angobject of the present invention :to provide a modified action characterized by the .gen-1 eral vfunctional features just outlined.

It is an 'object of the invention to `provide .an improved action characterize-d lby .those 'func-v tional features.

In the action disclosed in the lest-mentioned co-pending application theeleinents which-came into vimpingernent with .each other to vexert 'the braking effect were the hammer and the :hackc'heok. It is an objectof lthe present .invention to provide alternative karrangeri/lents of-those ele;1 ments, wherein theywill still, hawevencomeinto impingement witheachothersto exertithe braking effect.

In theaction disclosed inthe last Amentioned (zo-pending application the impingement between the elements above referred to occurred asia re sultof an loscillatory swing of 4one oizthose elements from its normal or sloiv-motion'path. :It isansobject of the presentv invention togprovidean arrangement in Vwhich the `impingement between the elements requirediior the brakingeiect is not dependent on an oscillatory nature =of swingiof either .element (though .such a swing is 'permissif ble), but may be caused by a simple vunilateral displacement of onefof the elements.

Y,In .the action disclosed in theiast mentioned cra-pending application the diression or one of theielements from normal or'slow-motionpath .to occasion the braking effect wasa lateral displacement. Itis an object of `thepresent invention to utilize 'a terminal overshooting-.oi the .normaler slow-motion `path as zthe digressioncausing the braking effect. Y

In the action .disclosed in :the .last -inentioned cao-,pending application the element arranged to digress significantly from its normal path to'cause the braking eect was the hammer. It-is v,an objectoi the :present invention to effectively utilize the back-fcheck asthedgressing one or" the elements.

.In an action ,embodying the broad principles disclosed inthe last mentioned (zo-pending application there may be associated with one of the e1ements,.to cause and control its digression, both a resilient means 'and 'a mass. It is Aan object 'of the present invention toassociatesuch aresilient means'andmasswith the back-check in a particu-` larly convenient and effective manner.

-Other-andallied objects-Willimore fully appear iromthe -iollowing description-and the appended claims.

'In the descriptionfoffm-y invention hereinafter set lforth, vreference kis had :to the accompanying drawings, offwhich Figure 1 is an elevational view of one embodiment of my invention, incorporated in an action of the grand-piano type;

Figure 2 is an elevational view of a portion of the apparatus of Figure 1 but illustrating the same with the components in positions which they occupy at a certain stage during operation;

Figure 3 is an elevational view of another embodiment of my invention, incorporated in an action of the upright-piano type; and

Figure 4 is an elevational view of a portion of the apparatus of Figure 3 but illustrating the same with the components in positions which they occupy at a certain stage during operation.

In Figure 1 the numerals I, 2 and 3 respectively designate the front, intermediate and rear rails of the key-assembly portion of a piano action. Extending upwardly from the rail 2 is shown a pin 4, encircled by a bushing or pad 5; and a key 6 is shown pivotally assembled on that pin and resting on that pad. The front end of the key extends over the rail I, which is provided with the guide pin 'l extending upwardly and freely into the key, that pin being encircled by the bushing or pad 8 underneath the key. The rear end of the key is shown in its normal position of rest against the top surface of the strip or pad 9, which in turn is secured on the top surface of the rear rail 3. Between the pivot pin 4 and the rear extremity of the key, the key 6 isV provided with the upwardly extending capstan screw IEl. The key assembly as so described will be recognized as well known.

Driven by the capstan screw I0, upon operation of the key 6 (i. e., downstroke of its forward extremity), is the hammer II. This may be considered as comprising the hammer head I2; the hammer stem I3, at the rear end of which the hammer head I2 is attached; the hammer butt I4, in which the forward end of the hammer stem I3 is secured; and the pad I6 secured to the lower surface of the hammer butt I4. The butt I4, and thereby the entire hammer II, is pivoted at I1 to a flange I8, which in turn is secured to a suitable rail' I9 in the action.

The hammer II is coupled to the capstan screw It, so as to be driven by the key 6, through asuitable coupling member such as 51. This may be in the form of a cylinder, for example of metal, with each of its end portions spun over into end-closing formation excepting for a relatively small central aperture-as shown in Figure 1 for the upper end of the member 51. In and extending downwardly from the hammer butt I4 through the pad I6, a short distance rearwardly from the pivot I1, there is secured a small pin 53; and in and extending upwardly from the capstan screw I Il there is secured a small pin 54. The parts are so positioned that the pin 53 is disposed approximately above the pin 54. The coupling member 51 may extend from the `pad I' to the capstan screw I0, except- -ing that a pad 58 of thin felt or the like may intervene between the top of the capstan screw and the bottom of the coupling member. The pins 53 and 54 respectively extend freely through the apertured ends of the coupling member.

The string which the hammer II is to strike is shown as 20, horizontally disposed above and in the path of movement of the hammer head I2 when the hammer pivots about I1. It will be understood that upon operation of the key 6 the attendant upward movement of the coupling member 51 will rock the butt I4 upwardly about 4 the pivot I1, carrying the hammer head I2 toward the string.

The capstan screw It may be so adjusted that at the conclusion of an abnormally slow operation of the key-i. e., one so slow that the Coupling member remains in contact (through 53) with the capstan screw and the pad I5 remains in contact with the coupling member-the active (top) end of the hammer head I2 will have brought to a small distance from the string 2t; this distance may be comparable, for example, to that to which in a conventional action the hammer head has been brought at the time of tripping The normal position of the hammer will be fixed by the resting of the butt I4, through pad I6 and coupling member 51, against the capstan screw Il), and the resting of the rear end of the key through pad i) on the rear rail The downward displacement of this normal hammer position from the position occupied by the hammer at the conclusion of key operation (e. g., the key operation mentioned in the preceding paragraph) will of course be determined by the distance through which the capstan screw It moves during key operation-and this distance of capstan-screwv travel is in turn established, as conventionally, by adjustments of the eiiective thicknesses of pads 3 and 5 (as by choice of the thicknesses of stacks Sa and 5a of paper or cardboard washers with which the xed-thickness pads 8 and 5 may be supplemented), which adjustments of course nx the length of keystroke (as well as the normal key leved).

Though not indispensable, it may be desired to provide some form of stop against overshooting of the hammer downwardly up key release (due to momentary yieldings oi various parts such as pads I5, 9, etc). Purely by way of example there has been shown under the hammer stem I2 a pad 23 of soft felt or the like, secured to the top of a removable rail 24. The positioning of the rail 24 and the thickness of the r pad 23 will be such that on downward hammer movement to slightly below normal hammer position the hammer stem I2 will impinge against the pad 23-from which it will, however, normally have a slight spacing. Y

Simply by way of simplification of illustration, there has been omitted from Figure 1 any showing of the usual damper for the string 25; this may, however, be provided in any conventional manner.

When the key is operated the hammer will be propelled toward the string, until the forward end of the key bottoms on the pad S. At this point the movement of the key and of the coupling member 51 will be essentially stopped; in the case of stronger blows administered to the key, however, the key and coupling member will continue their movements for a small further distance with the pad 3 is being compressed to a slight degree, but any such continuance is at sharply reduced velocity. (Key and coupling member may execute a still Jfurther excursion, though only momentarily, while the upward inertia of the rear portion of the key momentarily causes a slight lifting of the key from its resting on padv 5; any such excursion will be relatively minute, however, and if troublesome in any degree may be precluded by means such, for example, as are shown in connection with a later onpad 8, and has acquiredan upward-inertia of its own. At `this time, 'being free yto continue -its movement, it ceases to 'be propelled by the nowstopped or much-slowed coupling member, and moves on without discontinuity of velocity to strike the string. vIt produces an initial upward deflection `of :the string; `it then moves downwardly with `the string as the latter .accelerates from its deflected position back toward its normal position, thus starting a -rebound from :the string.

As the string passes through its normal position and decelerates in its downward movement, the lhammer under its own inertia (as well as gravity) leaves contact with the string and continues .its rebound downwardly through lthe small distance required to bring it Vinto impingement against the coupling member l-assuming the -key to have remained in operated position since the propulsion of the hammer by it. Of course if the -`key has not remained in operated position Gi. e., if it has been released promptly after 'being struck) the downward passage ofthe hammer Will continue through the very substantial distance required to restore .it to its normal (Figure 1) position. yWhile it will tend to overshoot that position, there have already been described means (-i.e.,"pad 23) for relieving any resulting strainsand the hammer will be so far from the string that any re-rebounding'toward the string is quite harmless.

' If, however, the key has remained in operated position the hammer, upon passing through Ithe small distance required to bring it into irnpingement against the-coupling member 57, will come into such impingement and will then, Vby itsinertia, cause a temporary compressionoi various compliant members in the system, including the `hammer stem I3, the pad l5, the pad 5, the pad 58, and various other compliances (including the equivalent compliance of the pad 8 if that-is then being compressed by pressure on the key, in that there will be occasioned a temporary de-.compression of that pad), the hammer moving downwardly at decreasing .velocity while yielding up its energy to those compliances. The vhammer will then be moved upwardly, by the release of the energy acquired by those compliances, at `a Vvelocity which increases until the hammer `has reached the point at `which it began the compression of those compliances, by which timeall .the energy it delivered to those compliances (reduced yonly by dissipation therein) will have reappeared li-n the hammer in the form of upward inertia.

The foregoing outlines the action of the hammer in the absence of appropriate counteractive measures. And it `will be understood that :if such counteractive measures are not applied, the'hammer will respond to its own inertia by continuing on toward the string, and will re-strike the string excepting in the special case of arelatively weak original striking. Upon rebounding from the string after the re-striking, or dropping .down again without re-striking in .the special case just mentioned, the hammer will enter the second cycle of an oscillation to and from thecoupling member 51 'which oscillation may be considered to have begun when the hammer rst rebounded from the string after the original, .intended striking. The only limitation of the number of vcycles of this oscillation, in the absence of counteractive measures, is provided 'by the gradual dissipation of energy in the system-and the hammer may re-strike the string in as many as several of :the early cycles of the oscillation. vIt was to prevent such tonally'ruinous occurrences that :the escapexnent mechanisms of rconventional actions were resorted to andare still employed.

According to the principles `employed both Vin the disclosureof the last abovementioned cependingapplication and in the instant invention, vI'apply a braking-force rlto 'the hammer during itsattempted .oscillation A.to and from the coupling member 25.1 by such application .Illimit theoscillation to .a harmlessly zlow magnitude and rapid attenuation. I apply this vbraking force in progressively greater .degree the vhigher the velocity of 'key operation, with the results not only that the Abraking parts are saved .from needless xwear, but l.also that :full reliability of operation is .insured. And I `limit the Aapplication .of braking force to the lperiod .of attempted oscillation .of the hammer, notonly avoiding. interference .with the prior propulsion of hammer-to. string, butalso leaving the hammer Vquite unbraked `by the time it .concludes Iits attempted .oscillationwith the result that there yis no interference whatsoever (such as occasioned in a conventional .grandpiano action by a tight engagement of hammer tail with :back-check) with immediate repetition.

Both .in .the priordisclosure and inthat of the instantapplication the braking means istypically formed by vthelhammer as one element; lby a second element `^with which the .hammer may enter into impingement at proper times, to result `in the frictional relative movement .which is characteristic of a braking action; and by means `for causing impingement between the .two elements, or in other Words rendering the braking means effective, at theproper times. As in the priordisclosure, I may again conveniently Vutilize for the second element .a checking mechanism or backcheck of which the hammer-engaging portion maybe Yformed in general similarly to that of a conventional grand-piano back-check. According to the illustrated embodiments of the present invention, however, .it is in the back-check .or non-hammer element ofthe .braking means that I incorporate the means 4for renderingthe braking means effective.

In-Figure 1 .the back-check iis ldesignated generally as 40. -Its portion arranged for immediate cooperation -with the hammer :may be formed by ablock .42 of'wood or other relatively hard'material; a-padliil of relativelyfsoft felt or similarmaterial secured against the upper forward surface of the block 42; and a facing 44 ofileather or the like secured to the rear-top and forward-bottom portions of the black .42 and encircling the pad 43. 'The block .42 may be secured `onthe top extremity of'a rod M, the bottom end of which is fastened in a weight 4.5, This weight may be disposed within a recess 6' in the'top of the-rear portion of the key 6 .and .maynormally rest, for example, on the .bottom of that recess through a pad45 of fairly hard vielt or other slightlyyieldable material. Secured to the top of the vweight 46 is the rear extremity of a ilat .spring 4l, the forward lextremity of which is secured (as by screw 41a) to the top of the key 6 slightly forwardlyv of Athe recess .6

The ytrent surface of the back-check is preferablyarraiaged so that, `progressing upwardlyv from the bottom, it gradually .accomplishes a very slight vreduction of its separation from the hammer pivot l'f'l. The top surface of the back-check may be a convex one, progressing from the front surface along an arc of relatively small lradius centered within the upper .portion of the `backcheck. The result of lthis 'preferred construction is to provide, near the top elevational level of the back-check, a horizontal line or narrow region 40 whose separation from the hammer pivot l'i is less than that of any other part of the hammer-cooperating portion of the back-check.

The part of the hammer against which the back-check exerts its braking effect may be a hammer tail l5, generally similar to that conventionally provided in grand-piano actions. Such a hammer tail has been illustrated as 55, formed for example in the usual manner by a downward extension of the wooden core of the hammer head l2. While it is not indispensable, I prefer to incorporate in the hammer tail l5, to form its rear surface, a facing ld of leather or similar material. The hammer tail I is desirably so Y shaped that the bottommost portion of the rear surface is rounded off downwardly and forwardly from the immediately higher portion, which latter may be approximately arcuately shaped about the hammer pivot il, the two portions merging smoothly at the horizontal line or narrow region Il'.

The relative elevations of the regions le on the back-check and i i on the hammer are preferably so established, by appropriate design of those two elements, thatI these regions are approximately opposite each other when the key, having been depressed very slowly, is being pressed against the pad 8 with force equal to that with which it is so pressed at the conclusion of a relatively strong blow on the key. The relative foreand-aft positions of the back-check and hammer are preferably so established (and, for example, finely adjusted by bending of the rod dl) that the path of the back-check region Lit (which during the slow key motion has pivoted about the top of the pad 5) will just have arrived at an intersection with the path of the hammer region il (which of course pivots about Il) under the same conditions. These conditions are those under which the parts assume substantially the positions illustrated in Figure 2.

The designations i l and lill" may be assigned to regions, on the surfaces of the hammer and back-check, respectively, each of which embraces the respective region ii' or d abovementioned andadditionally includes a small surface portion immediately thereabove. It is between these regions i and 4Q that impingement occurs at appropriate times between the hammer and the back-check,

The means which causes this impingement at those times is comprised in the back-check. It typically includes the weight iii and the spring l already mentioned. It will be understood that the spring it? constitutes a resilient or flexible portion; further, that this together with the mass ofthe weight 45 (augmented by the effective mass of the portions lI-AZ-B-M. of the back-check fastened to the weight) forms a unilateral mechanical oscillating or swinging system.l The term unilateral is employed in view of the fact that swings in one direction (i. e., of the weight toward the key therebelow) are precluded by the normal resting of the weight through the pad 5 on the key. Swings in the opposite direction, however, are not precluded, and it is upon these swings that dependence is placed for bringing the regions Il" and 4t into impingement with each other to occasion the braking of the hammer.

' Thus when the key 6 is depressed at any substantial velocity the mass, Ymentioned above, of

energy. When the key impinges on the pad 8 and the key velocity executes a rapid reduction to zero, the kinetic energy of the weight will cause the back-check to execute an excursion from its normal relationship to the key. The very rst part of this excursion will comprise the release of such compression as the pad 45 may normally be subjected to; but the excursion will continue, with the weight A6 rising for a distance away from the pad. The upward velocity of the.

weight will of course be reducing and will eventually reach zero-at an interval after theY beginning of the excursion determined by the mass' abovementioned and the stiffness of the spring 'i-whereupon the weight will start downwardly toward the key and will come back into irnpinge-V ment against the pad 45. The weight will thentcnd to temporarily compress the pad tol a greater-than-normal degree, then to move upf;

pad 45, of a more viscous (i. e., energy-absurd,

tive) material such, for example, as Butyl rubber.

So long as the weight 4t moves with the key.-A the back-check movement is a pivotal one about, the top of pad 5-thus being very nearly vertical,

its path forming a relatively oblique angle with the path of movement of the hammer region. The continued movement of theback-check.

Il. just described, however, becomes a pivotal one about the effective point of its securing (i. e., the securing of the spring 41) t0 the key. lt will readily be appreciated that this latter movement,A

as felt at the region 40, has a large forward component (e. g., of the same order of magnitude as the vertical component) and that it is therefore much more nearly at right angles to the path. In the absence ofy of the hammer region Il". any screw through the spring 41 other than the screw 41a which secures that spring to the key,

the effective pivoting point for the continued..

back-check movement would be substantially at that screw. I prefer,.however, to employ another screw 41h alittle to the rear of screw 41a, passing' the screw 41h freely through the spring and on.;

down into the key, which I provide with a slight recess 6" (merging into the larger recess 6' to the rear of it) underneath the spring at this fore,-l and-aft position. By turning the screw lt'lb I am able to adjust the pressure with which the;

weight 4S normally rests on the pad 45, and to some extent the effective stiffness of the spring 41. The presence of the screw 41h of course. causes some rearward displacement of the effec" tive pivoting center for the continued back-g check movement. When key depression has been carried to theA point where the key first touches the top of the pad 8, the hammer will have reached a position a trifle lower, and the back-check a position a trifle lower and more rearward,.than the positions typically illustrated in Figure 2. The key movement then being rapidly slowed to zero, the` two relements just mentioned will nevertheless continue their respective movements. In view o f the 1 .back-check acquires substantial kinetic 15 its many-times greater Velocity, and assuming an.

atea-toa appropriate establishment of themass and stiff- Mness of the back-check elements, the hammer'will Ahave passed its Figure 2.position sooner thantypically, it will have reached-the'string when- -the back-check has reached its Figure 2.position.

As the back-check'passes its Figure 2 position its-region lill intersects the path of movement of the hammerregion II. If at this time the hammer has already rebounded somewhat from the string, impingem'ent'of the region 40 and the region I I will occur substantially forthwith. If the hammer hasnot yet significantly reboundved, its `region II will be above the back-check region 40', but still elevaticnally opposite and close to some higher part of the .region 40- and the iirst small interval of hammer rebound will be suiiicientfor the movements of backcheck and hammer to occasion impingement of the region im and the region II?. In any case vthe region itil 4and the region II will come into impingement with eachother, and the hammer will drive down for an interval in contact with the back-check-the parts (especially the pad 43 in the back-check) yielding while that contact continues. v

This contact,since it depends on the unilateral swing of the back-check out of normal relationship to the key, is of course temporary only-and, since it is inuenced by the magnitude of the swing, its duration -will be less with low thanwith vhigh key velocities. -Its :duration -is ample, however, `for the resulting frictional energy dissipation `to attenuate the-energy of the rebounding hammer amply to preclude its reaching the string on any re-reboundfrom the-coupling member 57,

if `not to preclude any such re-rebound altogether-and the shorterfduration with lower key velocities is entirely permissible since the braking requirements are inherently less with those lower key velocities. It will further be understood that the temporary nature ofthe contact leaves the hammer free'of any continued restraint by the back-check, so that perfection of repetition is assured. y

The choice of mass of the weight 46 'and stiffness ofthe spring 41, while-important, is in no Vsense critical. `And with any :given values of those parameters a considerable -latitude for adjustment -is provided by L the screw lib abovementioned.

In Figures A3 and 4 I'have-illustrated an embodiment of my invention in an action for use in an upright piano. 1 Herein ythere appear, as in earlier iigures,` the -rails l, 2 and 3; the pivot pin 4; the pad 5; the 'key 5; theguide pin l; the pad 8; and the strip The keyat its -rear extremity may carry the pad H of relatively hard felt or, if desired, of more viscous-material such-for eX- ampleas butyl rubber. Onthis pad may -normallyrest the round head I I llbof an adjusting screw I I0 hereinafter mentioned.

The hammer appears as III, and includesfa rearwardly directed head H2, a stem II3 at the top of which thehead II2 Vis carried, and a butt lid-from which the stem II3 vextends upwardly. The butt lle is pivoted at II'I `to a ange I I8 which extends -rearwardly from the :pivot to be `secured to the top fof fa suitable rail 122. The butt IM is provided with a forwardly extending .shoe I lia through which, at a little distance from the main body of the butt, there passes the adjusting screw II@ -abovementioned The top of 'this screw may 'be provided with -a screwdriverfslot II llc for adjusting purposes, while the Abottom of the screw `may be formed into the 'round `head IIDb already seen to rest normally `Von-th'epad Il. A spring I2I, one extremitylof which appears yin Figure 3, may be employed --in association with the pivot II'I to lightly urge the hammer forwardly about the pivot.

-The string which rthe hammer lil is to strike is shown ais d20, vertically disposed behind and inthe path of movement of the hammer head H2. It'will Abe understood that upon depression of vthe key the upward movement of the pad IIS will rock upwardly the screw l IG, thus rocking the entire hammer and carrying the head -II2 toward the string. The screw vIl!) may be so adjusted that at the conclusion of an abnormally slow depression 'of the key the hammer head H2 will have ybeen brought to a relativelyfsmall distance from the string. The normal position'of the-hammer will be Xed by the resting of the screw IIll on'the pad Il and the resting of-the rear end of the key on pad tie-all Iin analogyto the xingof the'norrnal position of the hammer in the earlier-*described embodiment of my invention, and lsubject to similar comments as to adjustments.

As a stop against "overshooting of the hamme'r forwardly upon keyrelease (due to momentary yieldings of various compliant parts), ywith consequent strain on the hammer stem v'I I2, there may be providedarail I 24 carrying a strip 'I23 of -soft felt or the like 'o'n its -rear surface, in -such a .position lthat on forward hammer 'motion to slightlybe'yond normal hammer position the front end of the hammer head H2 will irnpinge against the strip I23-from which it will, however, normally have a slight spacing. fIf fit v-be desired that the hammer at times have fa reduced spacing from the string I-Z, the Irail |24 may -be moved rearwardlyfor which '-purpose it has been shown as forming the Acrossarm of a bail one of whose side-arms appears as |25, pivoted at |26 to permit the just-mentioned rearward movement (which may be effected vby the usual soft pedal, not shown). As usual under conditions of less-than-normal hammerto-string spacing, the vkey-'hammer `contact (at IIG--I'Ib will be Avopened up until some initial portion of key depression has been completed.,` -As astop against momentary overshooting upwardly by the rear end of the key-which rmay tendto occur as a resultof the key momentarily rising out of Contact with the pad 5 at the'conclusion vof adepression of its forward end-I have -shown a stop member i121 extending forwardly from the rail 122; vthe surface of this stop mem- `ber may be provided with a covering I'ZIa of slightly compressible and preferably viscous material such, lfor example, as butyl rubber. A

'shoe II'S'a may extend rearwardly `from the rear end of 1vthe key under the stop member i271, at such Van elevation that upon key 'depression it will essentially exhaust'the compressibility of the covering 'I2'Ia lwhen pressure on the front end of the 'key has essentially exhausted the cornpressibility of the pad 8. The use of such a stop membeh 'Which-is ofcourse not limited to the presently described embodiment, will be understood'simply to insure that behaviour of the rear end of the key which is to be expected from the manipulation'of the front end of 'the key.

It vwill be understood that, with the pad I' considered as 'replacing `the coupling member 51 of the earlier-described embodiment, the same 'generalorganization of elements is present'as in that-embodiment; that the manner of basicoperation, subject only to VVthe `obvious interchange 1l of rearward for upward hammer movement, is similar; and that similar hammer-ose' lation problems are encountered and must be dealt with. In this embodiment I employ essentially similar means for solving those problems, but with variations appropriate to the altered arrangement of the hammer relative to the key. Thus I again employ a back-check carried by the key, and a hammer tail with which the back-check may come into impingement; but whereas in the earlier-described embodiment the back-check was arranged to cooperate with the outer face of the hammer tail (i. e., the face more remote from the hammer pivot), I reverse that arrangement in the instant embodiment and place the backcheck so as to cooperate with the inner (or pivotward) face of the hammer tail.

By way of optional variations not necessarily peculiar to the present embodiment, I omit from the active surface of the hammer tail therein any covering such as the leather or similar facing Ia of the earlier embodiment; and I continue the active hammer-tail surface smoothly to beyond the outermost point or region thereon where the back-check could impinge, thus eliminating any such feature as the rounded-01T bottom extremity of the hammer tail of the earlier embodiment.

The hammer tail in Figures 3 4 is designated as H5; while no limitation thereto is intended,

-it is shown formed as an attachment to the core of the hammer head H2, rather than as an integral piece therewith. From its secure attachment to that core the tail I l5 extends diagonally downwardly and forwardly. Starting at a point I H5 part-way out along the tail from the hammer head proper (which point is closer to the hammer pivot Hl than is any part of the tail nearer the stem H3), and continuing on to the end H5" of the tail, the inner (pivot-ward) surface of the tail H5 is approximately arcuately formed, typically with a radius of the order oi magnitude of the separation between point H5 and pivot Hl, but about a center forwardly displaced from that pivot the end and outer surfaces of the tail may be of any convenient configuration.

The back-check in Figures 3 4 is designated generally as lili?. It may comprise a block 42', pad #i3 and facing All respectively similar to the corresponding parts of the back-check earlier described; the rod I4! extending generally downwardly from the block "l2 which is secured thereon, in this instance however from the longerdimension (rather than the end) face of that block; the weight M, from which the rod llli extends upwardly, and which is conveniently formed of a fiat strip of heavy metal twice folded back upon itself and clamped in its folded state by the screw ila threaded through its several folds; and the spring 41 at the rear end of which the weight |46 is secured, and the front end of which is secured to the tcp of the key by the screw ela. Beginning just behind the screw lila the key may be slightly reduced in height, as indicated at the slight shoulder 6'; and the *screw Mb may be passed freely through the spring 4'! and into the reduced-height portion of the key--for the same function as the screw 2lb of the earlier embodiment. The pad d5 of that embodiment may be replacedin this by a plugshaped pad M5 inset into the top of the key underneath the screw ila and normally borne on by the downwardly directed head |461) of that screw.

vThe back-check |40 is arranged with its facing 44 disposed toward the hammer stem l I3 and tail H5; with the key in rest position the backcheck may have only a slight spacing from that stem. Its portion 42-43-514 may be oriented so as to cause its portion furthest from the hammer pivot Hl" to be a horizontal line or narrow region Iil generally corresponding to 4S of the earlier embodiment; such orientation is readily accomplished by a bending of the rod lli! at a point a little below 52.

When the key, having been depressed very slowly, is being pressed against the pad with force equal to that with which it is so pressed at the conclusion of a relatively strong blow on the key--the conditions approximately illustrated in Figure e-the hammer and hammer tail will have been moved rearwardly about lil (bringing the hammer head to a small separation from the string), and the back-check will have been moved a smaller distance upwardly and forwardly about the top of pad 5. The parts may be so adjusted (nal adjustment being, for example, by turning of the screw la to lower or raise its head Mtb) that then the back-check region M0 is opposite (below) an intermediate portion of the inner surface of the hammer tail lying between H5 and H5" (which surface portion is conveniently designated as HI), and is just out of frictional contact therewith.

It will bevapparent that the back-checkspring 4l' together with the weight 46 augmented by the effective mass of the portions illl-42-43-44 fastened to the Y weightforms a unilateral mechanical swinging system analogous to the one described in connection with the earlier embodiment. As in that embodiment, when the key is depressed at any substantial velocity the mass of the back-check aoquires substantial kinetic energy, and that when the key impinges on the pad 8 this kinetic energy will cause the back-check to execute an excursion from its normal relationship to the key. As in the earlier embodiment, this further excursion will involve an upward and forward movement of the back-check about the screw #1lb as an approximate pivot. And, in correspondence with the earlier embodiment, the hammer will have passed its Figure 4 position slightly sooner than the back-check reaches its Figure 4 position, and will strike the string without interference from the back-check.

But as the back-check passes its Figure e position its region |40 nearest the hammer tail will have intersected the path of movement of the hammer-tail surface portion H i. If at this time the hammer has rebounded sufficiently from the string to bring the hammer-tail portion HI above the back-check portion |40', impingement betweenthe two portions will occur substantially forthwith. If the hammer has not yet rebounded that far, the back-check will continue its excursion for a minute further distance, and there will then occur an impingement. between the backcheck portion |40 and a hammer-tail surface portion slightly forward of the portion lH'- the radial formation of the inner surface of the tail I l5 about a center forwardly displaced from HT causing it to act against the back-check asa cam, thus rendering especially non-critical the exact region along that surface at which the impingement may occur.

Again, of course, the contact of hammer-tail and back-check is temporary only, is of duration dependent on key velocity, is ample in durav-v tion for the resulting frictional energy dissipa- QQQUSMBOB -i-,ion fte sumeiently attenuate the ,energy of :the

i-rebounding hammer, and `ver-y promptly leaves #the `'hammer in condition lfor effective repetition.

"In Figures 3--4 I Shave shown ,-a .damper |39,

` securedon "averticalrod 13| near the topoftthe latter. -The bottom portion of fthe trod 13| may tremity yof a flexible tape |33. This tape may extend forwardly, passing :alongside the hammer Stem il 3', and may terminate -Vin 'la iloop encircling asm-all spool |34. This spool may surround-and frictionally engage a rod |35 extending upwardly from the key 6 between the key-pivoting rod 4 and the rear extremity of the key. The tape |33 will be of such a length that normally it will be a trifle slack; upon key depression, however, the spool |34 will be moved upwardlyy and forwardly in an arc about the top of pad 5, and the tape will be pulled forwardly by the forward compo nent of the spool movement, taking the slack out of the tape and pulling the damper out of contact with the string. The distance of movement of the damper effected by key depression may of course be varied by sliding the spool up and down along the rod |35.

While I have disclosed my invention in terms of particular embodiments thereof, and with reference to a piano as a typical instrument and to a string as a typical vibrator, I intend thereby no unnecessary limitations. Modifications in many respects will be suggested by my disclosure to those skilled in the art, and such modifications will not necessarily constitute departures from the spirit of my invention or from its scope. which I undertake to dene in the following claims.

I claim:

1. In a key-operated action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator: means, continuously retained in a hammer-propelling path and moved by key operation to a limiting position in that path, for propelling the hammer toward the vibrator, to and from which means while in that position the hammer attempts to oscillate after striking the vibrator; and means, comprising a mass carried by and placed in motion by the key and a exible member interposed between said mass and the key, for braking the hammer during such attempted oscillation only.

2. In a key-operated action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator: means, moved by the key in a hammer-propelling path and retained in a limiting position in that path while the key remains operated, for propelling the hammer toward the vibrator, to and from which means while in that position the hammer attempts to oscillate after striking the vibrator; and inertiacontrolled means, carried by the key and responsive to the velocity of operation thereof, for applying to the hammer in such attempted oscillation thereof a braking force variable in accordance with such velocity.

3. In a key-operated action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator; means, moved by the key in a hammer-propelling path and retained lna limiting position 1in thatV path while the key remains operated, for propelling the hammer 'toward 4the vibrator, .to and .from -which `means while in that position the hammer attempts ato .oscillate after striking .the vibrator; normally inoperative means carried by Vthe key for brak- Ying'the hammer; a flexible member included in said braking means to permit its establishment in operative condition; vand inertia means included in ,said vrbraking means :and cooperating with said flexible member to maintain the 'brakingmea-nsin inoperative condition during hamrmer 'propusion ,but to place the braking :means in operative condition during such attempted :hammer oscillation.

4.111 a key-operated action for exciting `the evibrator'of amusicalinst-rument,.a hammer mo.vable to strike the vibrator; means, moved lbythe key in a hammer-propelling path and retained in a limiting position in that path while the key remains operated, for propelling the hammer toward the vibrator, to and from which means while in that position the hammer attempts to oscillate after striking the vibrator; a back-check 4moved by the key, free of interference with the hammer element when the key is operated at very low velocity; and means, included in the back-check and rendered eective by inertia upon operation of the key at higher velocities, for causing impingement between the back-check and the hammer during such attempted hammer oscillation.

5. In a key-operated action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator; means, moved by the key in a hammer-propelling path and retained in a limiting position in that path while the key remains operated, for propelling the hammer toward the vibrator, to and from which means while in that position the hammer attempts to oscillate after striking the vibrator; a back-check moved, normally free of interference with the hammer, by the key; a flexible member included in said back-check to permit impingement between the back-check and the hammer; and inertia means included in the back-check and cooperating with said exible member to maintain the back-check free of the hammer during hammer propulsion but to cause impingement between the back-check and the hammer during such attempted hammer oscillation.

6. In an action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator, from which after such striking the hammer rebounds; a movable key for propelling the hammer toward the vibrator; and means, moved by the key during key movement and rendered eiective only by its own kinetic energy acquired during such movement by the key, for frictionally engaging the rebounding hammer.

7. In an action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator, from which after such striking the hammer rebounds; a limitedly movable key for propelling the hammer toward the vibrator; and means, flexibly carried by the key and responsive to the abrupt stoppage of key movement, for braking the rebounding hammer.

8. In an action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator, from which after such striking the hammer rebounds; a movable key for propelling the hammer toward the vibrator, and stop means against which the moving key impinges; and means for braking the rebounding hammer, com- 15 prising la unilateral mechanical swinging system energized by key movement and svvingingly responsive to the impingement of the key against said stop means.

49. In an action for exciting the vibrator of a musical instrument, a hammer movable to strike the vibrator; a movable key for propelling the hammer toward the vibrator; and -a back-check moved by the key during key movement and thereafter subjected to movement by its own kinetic energy acquired during such movement by the key, the back-check being positioned to be engaged by the hammer during such further movement only.

10. In an action for exciting the vibrator of a 15 Number musical instrument, a hammer movable to strike the vibrator, from which after such striking the hammer rebounds; a movable key for propelling the hammer toward the vibrator; and a backcheck for the hammer moved by the key through a range free of interference with the hammer, both during` propulsion and rebound thereof when the key is very slowly operated, and means comprised in the back-check for extending its range of' movement in response to key operation at higher velocities.

' BENJAMIN F. MIESSNER.

REFERENCES CITED The following references are 0i record in the file of this patent: Y

UNITED STATES PATENTS Name Date 28,474 Hulskamn May 22, 1860 124,289 Rogers Mar. 5,-1872 179,397 Carr July 4, 1876 

